19Clay settling areas are large impoundments brought about by phosphate mining with 20 water-holding capacity that renders it very poor for agriculture and crop production. This study 21 aims to enhance water percolation in phosphatic clay using porous diatom frustules under 22 laboratory conditions. Phosphatic clay collected from settling areas was brought to the laboratory 23 for the experiment. Diatom frustules were purchased commercially and dry samples of the 24 diatom, Didymosphenia were provided by the University of Colorado-Boulder. Oven-dried clay 25 was mixed with diatom frustules into 125 mL centrifuge tubes following a 1:1 volume ratio as 26 experimental set-ups while pure phosphatic clay was used as control. Deionized water was 27 poured into each set-up and the percentage of unpercolated water overlying the sediment, water 28 retained in the sediment particles, water that percolated and passed through the hole of the 29 centrifuge tube were monitored for 48 hours. Results showed that the addition of diatom 30 frustules enhances the percolation of water in the sediment mixture especially those with 31 Didymosphenia frustules. However, this mixture also showed higher percentage of water 32 retained in the sediment particles which could be attributed to the high carbon and organic 33 content brought about by the presence of stalks which is a major component of this species 34 morphology. Considering how Didymosphenia disturbs freshwater habitats, proper management 35 may render it useful for the mitigation of clay settling areas in the land environment. The 36 implication of this on crop production remains to be explored and further in situ 37 experimentations need to be conducted. 38 IMPORTANCE 39 Clay settling areas abound in places where phosphate mining is conducted. The very fine 40 particles and the chemical property of this phosphatic clay allows it to hold water more than 41 3 normal clay sediments making the area unstable and less suitable for agricultural use. Studies 42 show that mitigative measures to enhance surface drainage is very costly leaving most areas 43 barren and unused. Diatoms are unicellular algae in various size and shapes with silicified cell 44 walls that are porous and are ubiquitous in aquatic environments. The significance of our 45 research is being able to demonstrate the potential use of diatoms, most especially the genus 46 Didymosphenia which is regarded as an environmental threat to some habitats, in mitigating the 47 drainage problem in clay settling areas by mixing phosphatic clay with diatom frustules. This 48 process is cost-effective and more importantly provides utilization of a resource that is regarded 49 as nuisance in freshwater environments. 50 104 Phosphatic clay: Diatom Mixture preparation and data analysis 105 A 1:1 volume ratio of phosphatic clay: Didymosphenia and phosphatic clay: 106 diatomaceous earth were weighed separately using a Mettler Toledo scale (SN B421637099) and 107 each sediment mixture was vortex-mixed thoroughly for 10 minutes. Five m...